Method for the synthesis of sulphur-bearing derivatives of high molecular weight



Patented May 2, 1944 UNITED METHOD FOR THE SYNTHESIS OF SUL PHUR-BEARINGDERIVATIVES OF HIGH MOLECULAR WEIGHT Bert H. Lincoln, Gordon D. Byrkit,and Waldo L.

Steiner, Ponca City, Okla., assignors to Continental Oil Company, PoncaCity, Okla., a corporation of Delaware No Drawing. Application SerialNo. 283,5

13 Claims.

Our invention relates to sulphur containing lubricants, and moreparticularly to a lubricant containing a sulphur bearing addition agent,substantially noncorrosive to the newer types of bearing metals now usedin present day automotive vehicles.

This is a continuation in part of our copending application Serial No.205,531, filed May 2, 1938, now Patent 2,218,132, hearing date October15, 1940.

Automotive engineers are using bearings containing cadmium andcopper-lead mixtures as well as high lead content compositions. Thesenew bearing compositions, while possessing certain mechanical advantagesover the old tin-babbitt hearings, are more susceptible to corrision.Oxidation and decomposition products of the lubricant react with thesebearings and often cause failure through corrosion.

One object of our invention is to provide a lubricant containing a newtype of sulphur compound which will impart increased film strength tothe lubricant while being substantially noncorrosive to the new typebearing metals.

Another object of our invention is to provide a sulphur containingaddition agent which is at once a film strength improver and a corrosioninhibitor.

A further object of our invention is to provide a lubricating oilcontaining a sulphur bearing addition agent which will reduce oxidation.with the resultant sludge and acid formation.

A still further object of our invention is to provide a lubricant havingincreased oiliness characteristics and color stability.

Other and further objects of our invention will appear from thefollowing description.

In general our invention comprises the addition of small quantities ofsulphur-bearing derivatives of high molecular weight petroleum fractionsto oils of lubricating viscosity. As little as 0.05 per cent of oursulphur compounds added to a lubricant appreciably increases itsresistance to oxidation and corrosiveness. As much as 20 per cent of thecompound may be added to a lubricant with beneficial results with July10, 1939, '70

respect to film strength and oiliness properties,

not by way of limitation, we will describe the method of obtaining ouraddition agent from a low melting point wax of from 18 to 24 carbonatoms. The wax is halogenated to a halogen content of from 8 to 12 percent. The crude halogenation mixture will comprise some unchlorinatedwax, mostly mo'nochlcr wax and some more highly chlorinated waxes.Chlorination of wax lowers its melting point stepwise inversely as thedegree of chlorination. A monochlor wax will melt lower than the likeunchlorinated wax. A dichlorinated wax will have a lower melting pointthan the monochloro wax. The unchlorinated wax may be separated readilyfrom the crude chlorination mixture by melting point differences, usingsweating, or selective solvent extraction at various temperatures.

A solution of the crude chlorination mixture may .be formed withacetone. At about F. the chlorinated waxes will be in solution, whilethe unchlorinated Wax will not dissolve and may be separated bysettling, centrifuging, or filtering. The solution may be chilled toprecipitate the monochloro wax. Thus the monochloro wax may be separatedfrom the polychloro wax employing the same methods as these outlined forseparating unchlorinated wax from the chlorinated wax mixture.

The halogenated petroleum fractions thus obtained are treated so as tointroduce into the molecule one or more double bonds. Chlorine may bepresent in the final product. The sulphurizing reagents used includesulphur, hydrogen sulphide, alkali metal hydrosulphides, sulphides andpolysulphides, sulphur chloride and phosphorus pentasulphide. Thesulphurization may be carried out with or without the addition ofsolvents including hydrocarbons, such as naphtha, light lubricating oiland the like, halogenated solvents such as trichloroethylene,pentachloroethane and the like, water, and al cohols. It is advantageousto heat the components together under elevated pressure. Thesulphurizing agents may be used alone or in admixture with one anotheror one. after the other. According to the conditions and reagents, thedouble bonds are entirely or partly saturated by the entrance of thesulphurizing agents or the halogen atoms are entirely or partly replacedby the sulphurizing agents.

It should be pointed out that olefinmade as described in a definite typeof compound having the structure When prepared from a paramn wax R is analiphatic group containing 1 to about 20 or more carbon atoms. The sumof the two R's should be between 10 and 60 carbon atoms. When the olefinis prepared from a wax, a high boiling mineral oil, or mixture of waxand mineral oil, a specific type of structure is always obtained. Insulphurizing this type of compound the sulphur adds on to the doublebond and none is substituted for hydrogen, as is proved by the fact thatin the sulphurization practically no hydrogen sulphide (HzS), is formed.This fact makes it possible to prepare a definite type of sulphurcompound in contrast to the heterogeneous mixture which is obtained whena. cracked petroleum derivative containing many types of unsaturates issulphurized. The advantages of the former, due to its relative purity,are manifold.

In sulphurizing the olefin we may use elemental sulphur or variouscompounds of sulphur including sulphur monochloride, sulphur dichloride,phosphorus pentasulphide, phosphorus trisulphide, polysulphides, and thelike. Each of these reagents gives somewhat different products.Furthermore, by variations in the conditions of sulphurization, we mayobtain two general types of products from each reagent regardless ofsulphur content. One of these contains some active sulphur, and thegather contains no active sulphur; that is, all the sulphur is in aninactive form. By active sulphur we mean that form which is present whena per cent blend of the sulphurized material with 90 per cent ofgasoline, kerosene, or a lubricating oil (itself free from activesulphur according to this test) will appreciably discolor a brightcopper strip immersed therein and held at 210 F. for 30 minutes. If thecopper strip is not appreciably discolored, all the sulphurpresent is inan inactive form.

Both types of sulphurized products are useful for different purposes.For example, materials containing active sulphur are more efiectivecomponents of gear lubricants and the like where extreme pressure isused and no easily corrodible metals are present. For crankcase use,however, especially where bearlng metals sensitive to corrosion areemployed, our product containing only inactive sulphur is preferred.

Various factors must be considered in the preparation of our sulphurizedolefin containing active and inactive sulphur:

1. Reagent: In general for the preparation of sulphurized olefincontaining active sulphur, we prefer to use elemental sulphur combinedwith short times of heating and lower temperatures. The sulphurcompounds such as chlorides of sulphur and sulphides of phosphorus aremore likely to giveproducis containing only inactive sulphur and are notso flexible with regard to variations in other conditions as sulphuritself; however it is possible to use sulphur compounds to obtainproducts with active sulphur.

2. Proportionsof reactants: For the preparation of products with activesulphur, we prefer to use large proportions of sulphur or sulphurcompounds because it is easier to obtain the desired product, otherfactors being constant. It is possible, however, at lower temperaturesand with shorter periods of heating especially in $01- vents, to obtainactive sulphur containing products using small amounts of sulphur. Bycontrolling reagents and conditions we are able to obtain sulphurbearing derivatives of our olefins with 2 to per cent or more sulphur.For any given sulphur content, we may obtain products containing activesulphur or containing only inactive sulphur.

3. Temperature: Higher temperatures tend to fix the sulphur in inactivecombination and are used when a staple sulphurized olefin is desired.

Use of lower temperatures with the same reagents and otherwise the sameconditions gives products containing active sulphur which are especiallyuseful for cutting oils and extreme pressure gear lubricants whenblended with hydocarbon oils and other ingredients.

4. Time: We heat our reactants for a relatively short time to producematerials with active sulphur and for a relatively long time to obtainonly inactive sulphur in our products. A short time at a hightemperature may be selected .which is the equivalent of a longer time ata lower temperature within certain limits. There is, however, a mostsuitable range of temperature below which the time required isunreasonably long.

5. Solvents: Inert solvents may be employed; and, in general, they havethe efiect of limiting the highest temperature used in a particularsulphurization. If the solvent does not dissolve the sulphur or sulphurcompound appreciably, the rate of reaction is slower and the formationof products containing active sulphur is favored. If the solventdissolves the sulphur or sulphur compound, the reaction proceeds morerapidly; and products containing only inactive sulphur are more readilyobtained.

6. Unrefined products are more likely to contain active sulphur thanrefined products. We vary the quantities of refining reagents, forexample, sulphuric acid and clay, and also their concentration, time andtemperature of contact, etc., to obtain thorough refining when a verystable product is desired. The refining may be milder or even omittedwhen an active su phur product is sought.

'7. Pressure: Under superatmospheric pressure the sulphur is more stablyfixed in the same time and under the otherwise same conditions, and thisis a useful modification of our process in order to obtain productscontaining only inactive sulphur.

Example 1 Stoddard solvent (boiling range 300 to 400 F.) is treated withchlorine until it contains about 25 per cent chlorine. This is heatedwith one quarter its weight of sulphur for several hours at 350 F. withstirring. Product is dissolved in alcohol and filtered from unchangedsulphur, and then the alcohol is distilled off. This material is blendedwith heavy oils to produce an extreme pressure gear lubricant.

Example 2 One hundred parts of the olefin are chemically combined with10 to 15 parts of elemental sulphur, sulphur chloride, or phosphoruspentasulphide. This is accomplished by heating and stirring attemperatures from 300 to 360 F. Amounts of sulphur or other sulphurizingreagent and temperature outside the given ranges may be used with lesssatisfactory results. A

short time of heating is sufiicient when a prodnot containing activesulphur is desired. The heating is continued until all of the sulphurhas chemically combined when a product containing only inactive sulphuris desired. Improved results are obtained by first mixing the olefinwith about an equal volume of refined mineral oil before sulphurlzing.The sulphurized olefin thus prepared is now ready for use in a varietyof lubricants such as gear lubricants, extreme pressure lubricants, andcutting oils. It is merely blended with a suitable base oil inproportions 1 of 0.05 to 20 per cent or more, depending on the amount ofsulphur required in the lubricant. These blends yield superiorlubricants compared to the corresponding blends made from the well knownsulphurized fatty oils in that they contain no glycerine either free orin combination. Glycerine compounds in a lubricant are prone to causegumming of mechanical parts and are less stable than the sulphurizedolefin lubricants. A further important superiority of the latter is therelatively low viscosity of the blends at low temperatures compared tothe viscous blends that result when sulphurized fatty oils or glyceridesare used. We are aware of prior art which describes lubricantscontaining sulphurized unsaturated hydrocarbons from the cracking ofmineral oil. In the old art a conglomerate mixture of compoundscontaining some unsaturates is sulphurized. There does notappear to beany high boiling olefins present in this mixture, since it consists of acracked product; and the unsaturates are therefore cyclics. Onsulphurizing these, some sulphur will enter into chemical combination byhydrogen substitution, which is objectionable. The unsaturated, doublebonds in a cracked product are not of equal chemical activity; thereforethere cannot be an even distribution of sulphur throughout its mass,which is very highly undesirable. In our invention, we sulphurize arelatively pure olefin and obtain a relatively pure compound havingconstant, definite and uniform properties. Our product readily lendsitself to refining. It does not contain any objectionable componentsafter refining.

When the sulphurized olefin is to be used as an inhibitor in a crankcaselubricant for protection of the new type bearings, it may be firstrefined. The sulphurized olefin should be treated to remove the usualtraces of impurities present. (This may be done by blowing with an inertgas or other suitable means.) The sulphurized olefin (or blend of olefinin mineral oil) is contacted with .5 to 3 per cent by Weight of 80 percent sulphuric acid for 5 to 30 minutes at 100 to 150 F. The sludge isallowed to settle thoroughly, and the treated product is transferred toa clean container and neutralized with iullers earth or the equivalent,such as activated carbon, bauxite, lime, or caustic, at temperaturesbetween 200 and 275 F. for 5 to minutes. The mixture is filtered toremove the neutralizing agent. The finished product has a color of about3 A. S. T. M., is odorless, and when blended with a lubricating oil doesnot afiect the color or the emulsion test as do the sulphurizedgiycerides. This will be apparent from the following test:

A S. T M.

Herschel fifig demulsibility S. A. E. 10 mineraL 30 (perl'cct) 1,620(perfect). 5. A. E. 10 mineral plus .2 per cent Srefinedlsulphuriaaledlolegn E do Do.

. A. E. 0 miner p us per cen refined sulphurized lard oil 90 (bad). 420(had).

The sulphurized olefin does not afiect the A. S. T. M. copper strip testof blends in lubricants even when run for more than 30 minutes at 210 F.The addition of .05 per cent to two per cent of this sulphur compound toa lubricating oil gives a lubricant which is practically free of anytendency to corrode .the new type bearings, as determined by theUnderwood corrosion oxidation of the lubricant.

test. The Underwood is an accelerated corrosion test and was developedby the General Motors Corporation and is iully described in theliterature. It consists essentially of a sump in which the oil is heatedto 325 F. The test pieces are half bearing inserts of the cadmium alloyand copper-lead types and are held in a rigid position in a smallchamber. Jets of the hot oil under 10 pounds pressure are impingedagainst these pieces. The test is allowed to run four hours or untilcorrosion starts. For a standard test, the mineral oil is blended witha. lead soap to the extent that the blend contains .05 per cent leadoxide. The lead soap accelerates the corrosion gate. The following testshows the efiect of the addition of the sulphurized olefin on corrosionwith respect to cadmium alloy and copper-lead bearings.

Refined Mid-Continent S. A. E. 30, plus .05

per cent of PbO, plus .25 per cent of sulphurized olefin (after 4 hours)0 0 Refined Mid-Continent S. A. E. 30, plus .05

per cent of PhD, plus .25 per cent of sulphurized olefin (after 9 hours)0 10 The manner in which this inhibitor stops corrosion is notknown, butthe following theory gives a fairly satisfactory explanation. It is afact that some metallic oxides and soaps have a strong catalytic eiTecton the oxidation of mineral oil, which in turn gives rise to theformation of corrosive organic compounds; furthermore it is known thatthe metallic sulphides are illsoluble in mineral oil. It is assumed,therefore, that as soon as any metals, such as iron irom the engine andcopper, lead, or other metals from the bearings, start to corrode, theyform the relatively inert sulphides instead of the active oxides andsoaps, thus slowing down the rate of It is obvious then that a sulphurcompound to be a good inhibitor must not be too stable or it cannot giveup sulphur at a rate equal to the lubricants tendency to form oxidationproducts and soaps; furthermore it must not be too unstable or it willive up too much sulphur and cause corrosion from the action of freesulphur which would first manifest itself in the darkening of copperparts. The sulphurized olefin of our invention has just the correctdegree of stability.

The sulphurized olefin does not only stop corrosion of the new typebearings, but it also reduces the amount of oxidation of the oil. AStandard of Indiana oxidation test, which is fully described in theliterature, was run on a base oil and on the same oil plus .2 per centof sulphurized olefin, with the following results:

S. A. E. 30

Hours required to produce %h gfiigggg? ized olefin Hours Hours n umb 7.0 ll. 8

1.0 neutralization number. 12.8 18. 4 1000 true color 7. 2 3. 2 l6. 2l8. 0

2000 true color In practicing our invention, the relatively puremono-olefin which is obtained from the relative- 1y pure monochlor waxis sulphurized as was stated previously; however the olefins, dioleflns,and polyolefins resulting from the dehalogenation of dichlor andpolychlor wax or mixtures thereof with each other and with unchlorinatedwax may be used in preparing a sulphur base for use in a cutting oil,gear lubricant, or extreme pressure lubricant.

Our olefins are characterized by the fact that considerably more sulphur(a total of 20 per cent or more) can be made to combine with them byusing temperatures up to 450 F. than is obtained by saturating them at300 to 360 F. with sulphur. This holds true for the mono-olefins as wellas for the polyolefins. Prepared this way, they are able to hold insolution additional percentages of elemental sulphur. A sulphur base ofthis type is well suited for use in cutting oils,

etc. On the'other hand, we may, when desired, prepare sulphurizedolefins containing as little as two per cent of sulphur. The sulphurizedolefins of our invention may be blended with any mineral, synthetic,animal, or vegetable oil to improve resistance to oxidation, with itsattendant increase in sludge formation, and tendency to corrode metals.

We have discovered that our sulphurized compounds are enhanced in theiraction on blends in lubricating oils by the presence of other types ofcompounds. Halogen and phosphorus compounds seem in particular to havesuch an improving effect on the action of our sulphurized compounds. Forexample, we may add to a blend of any of our sulphurized compounds in alubricating oil such compounds as chlorinated paraifin wax, chlorinatedoctadecanol, dichloropropyl ether, chlorobutyrone, octadecyltrichloracetal, dichloromethyl stearate, chlorotolylstearamide,chloro-oleyl amine, chloro-oleyl amide, calcium dichlorostearate,pentachlorodiphenyl, a chlorinated wax-naphthalene condensation productcontaining residual chlorine, trichlorophenol, trichlorodiphenyl ether,chlorodiphenylene oxide, chlorophenylstearic acid,o-chloro-acetophencne, chlorobenzophenone, pentachlorophenyl-benzoate,chlorobenzanilide, chlorophenyl phosphate, chlorophenyl phosphite,chlorophenyl phosphine,

"phosphazine, phosphanilide, phosphazobenzene,

phosphorus iso thiocyanide, phosphoryl isothiocyanide and the like. Ingeneral, any halogen or phosphorus bearing organic compound having avapor pressure of less than atmospheric at 140 C. has been foundsuitable as an auxiliary addition agent to -our sulphurized compounds.

It is to be understood that the examples hereinabove given are by way ofillustration only and not by way of limitation and that the theoriesadvanced with regard to the action of our sulphurized olefins are ourconception of what takes place. We do not wish to be bound by thetheories but base our claims upon the improved results which areobtained.

It will be understood that certain features and sub-combinations are ofutility and may be employed without reference to other features andsub-combinations. This is contemplated by and is within the scope of ourclaims. It is further obvious that various changes may be made indetails within the scope of our claims without departing from the spiritof our invention. It is therefore to be understood that our invention isnot to be limited to the specific details shown and described.

Having thus described our invention, we claim:

1. A method for the synthesis of sulphur-' bearing derivatives of highmolecular weight, including the steps of halogenating paraffinhydrocarbons whose monochloro derivatives melt lower than thehydrocarbons themselves, separating substantially pure halogenatedhydrocarbons from the crude halogenated mixture, dehalogenatingsaidhalogenated hydrocarbons to form unsaturated hydrocarbons, andsulphurizing the unsaturated hydrocarbons by reacting with elementalsulphur.

2. A method for the synthesis of sulphurbearing derivatives of highmolecular weight, including the steps of chlorinating paraflinichydrocarbons whose monochloro derivatives melt lower than thehydrocarbons themselves, separating substantially pure chlorinatedhydrocarbons from the crude mixture, dechlorinating the said chlorinatedhydrocarbons to form unsaturated hydrocarbons, and sulphurizing theunsaturated hydrocarbons by means of elemental sulphur.

3. A method for the synthesis of sulphurbearing derivatives of highmolecular weight, including the steps of chlorinating a low meltingpetroleum wax, separating substantially pure monochloro wax from thecrude mixture, dechlorinating the said monochloro wax to form an olefin,and sulphurizing the said olefin by means of elemental sulphur.

4. A method for the synthesis of sulphurbearing derivatives of highmolecular weight, including the steps of halogenating a distillednormally liquid parafiinic hydrocarbon boiling above 300 F. to themonohalogen stage, separating the substantially pure monohalogenderivatives from the crude halogenated mixture, dehalogenating the saidmonohalogen derivatives to form an olefin, and sulfurizing the saidolefin by means of elemental sulphur.

5. A method for the synthesis of sulphur-bearing derivatives of highmolecular weight, including the steps of halogenating paraffinhydrocarbons whose monochloro derivatives melt lower than thehydrocarbons themselves to the halogen content corresponding themonohalogen compounds, utilizing differences in melting points toseparate substantially pure monohalo gen compounds from the crudemixture, dehalogenating by heating with lime at 200 to 550 degreesFahrenheit, and sulphurizing the resulting olefin with elementalsulphur.

6. A method for the synthesis of sulphur-bearing derivatives of highmolecular weight, including the steps of chlorinating paraffinhydrocarbons whose monochloro derivatives melt lower than thehydrocarbons themselves to the chlorine content corresponding" to themonochloro compound, utilizing differences in melting points to separatesubstantially pure monochloro compounds from the crude mixture,dechlorinating by heating with lime at 200 to 550 degrees Fahrenheit,and sulphurizing the resulting olefin with elemental sulphur.

7. A method for the synthesis of sulphurbearing derivatives of highmolecular weight including the steps of halogenating paraffinhydrocarbons whose monochloro derivatives melt lower than thehydrocarbons themselves separating substantially pure halogenatedhydrocarbons from the crude halogenated mixture, partiallydehalogenating said halogenated hydrocarbons to form unsaturatedhydrocarbons, and sulphurizing the unsaturated hydrocarbons by reactingwith elemental sulphur.

8. A method for the synthesis of sulphur-bearing derivatives of highmolecular weight including the steps of chlorinating parafllnichydrocarbons whose monochloro derivatives melt lower than thehydrocarbons themselves, separating substantially pure chlorinatedhydrocarbons from the crude mixture, partially dechlorinating the saidchlorinated hydrocarbons to form unsaturated hydrocarbons, andsulphurizing the unsaturated hydrocarbons by means of elemental sulphur.

9. A method for the synthesis of sulphur-bearing derivatives of highmolecular weight including the steps 01 chlorinating a low meltingpetroleum wax, separating substantially pure monochloro wax from thecrude mixture, partially dechlorimating the said monochloro wax to forman olefin, and sulphurlzing'the said olefin by means of an elementalsulphur.

10. A method for the synthesis of sulphur-bearing derivatives of highmolecular weight including the steps of halogenating paramn hydrocarbonswhose monochloro derivatives melt lower than the hydrocarbons themselvesto the halogen con-.

ing the steps of chlorinating paraffln hydro carbons whose monochloroderivatives melt lower than the hydrocarbons themselves to the chlorinecontent corresponding to the monochloro compound, utilizing diflerencesin melting points to separate substantially pure monochloro compoundsfrom the crude mixture, partially dechlorinating by heating with lime at200 to 550 F. and sulphurizing the resulting olefin with elementalsulphur.

12. A method for the synthesis of sulphur-bearing derivatives of highmolecular weight, including the steps of halogenating parafllnhydrocarbons whose monochloro derivatives melt lower than thehydrocarbons themselves, separating substantially pure halogenatedhydrocarbons from the crude halogenated mixture, dehalogenating saidhalogenated hydrocarbons to form unsaturated hydrocarbons, andsulphurizing the unsaturated hydrocarbons.

13. A method for the synthesis of sulphur-bearing derivatives of highmolecular weight, including the steps of halogenating paramnhydrocarbons whose monochloro derivatives melt lower than thehydrocarbons themselves, separating substantially pure halogenatedhydrocarbons from the crude halogenated mixture, partiallydehalogenating said hydrocarbons to form unsaturated hydrocarbons, andsulphurizing the unsaturated hydrocarbons.

BERT H. IJNCOLN. GORDON D. BYRKIT. WALDO L. STEINER.

